We’re getting closer to completely eradicating a human disease

Ajak Kuol Nyamchiek, 7, watches while John Lotiki, a nurse with the Carter Center, bandages the blister on her leg from where a guinea worm is slowly emerging in Abuyong, Sudan. Olivier Asselin/AP In 1986, Guinea worm was found in 21 countries across Asia and sub-Saharan Africa, and was thought to affect 3.5 million people annually.

As of last month, through the immense efforts of the Carter Center, there were just 22 cases of the disease reported globally in 2015, and it's now on the edge of becoming only the second human disease ever to be eradicated, after smallpox.

This astonishing achievement has taken persistent and dogged effort, involving the training of thousands of volunteers, the distribution of water filters, and the education of over 23,700 communities to the threat of the horrible parasite.

Even more impressive is that this has all been doable without the development of new technologies and without the need for medicines or vaccines.

The Carter Center was established by former US President Jimmy Carter in 1982, the year after he left office.

While the center works on a range of human rights and humanitarian issues, one of its main focuses is on neglected tropical diseases. These are illness that predominately affect developing nations and which, given the right attention, could be eradicated from the world.

"The Carter Center has the only international taskforce on disease eradication," Carter told IFLScience at a media event in London. "We are the ones that house the group that analyzes every human illness constantly, to ascertain which ones might possibly be eliminated or eradicated."

Extracting a Guinea worm is a slow and painful process. The Carter Center/L. Gubb While not lethal, Guinea worm is one of these neglected diseases and is incredibly debilitating.

After a person drinks infected water, the larvae hatch inside the body and then begin to grow in the abdomen.

The worms then mate and while the male subsequently dies, the female matures.

Around a year later, the female worms migrate down the limbs and create unbearably painful lesions on the legs and feet as they slowly emerge from the body.

The worms - which can reach up to a meter (3.3 feet) in length - can take several months to fully come out. During this process, the worms cause a burning sensation at the wound, often leading to the sufferers bathing the emerging worm in water as they try to seek relief from the pain. It is at this point that the female worms release their larvae into the water source, completing the parasites' cycle. Since these worms are dependent on human hosts, removing them from the environment represented a rare opportunity for complete disease eradication.

The dramatic reduction of Guinea worm hasn't been easy. Over the last 30 years, the program has faced multiple problems, many of which were unforeseen. One of the biggest issues was of conflict, with the civil war between Sudan and South Sudan hindering operations for 15 years. But war wasn't the only unpredictable event. "The other problem that we didn't anticipate was the involvement of some dogs that had Guinea worm disease in Chad," said Carter. "We'd had this in five other countries previously, and in every case when we'd got rid of the problem in humans, it goes away in dogs as well."

A small piece of steel mesh inside a plastic drinking tube offers a low-tech way to filter water on the go, preventing the small crustaceans that carry Guinea worm larvae from being consumed. The Carter Center/L. Gubb

The final major hurdle has been one of politics. "Sometimes when we get the total eradication and elimination in one country, the ministers of health and presidents of those countries get excessively confident and they go onto other priorities and abandon this," explained Carter. This is the threat that currently overhangs the present status of Guinea worm. With only a handful of cases reported last year, it is vital the pressure is kept on to ensure the total eradication of the disease.

It is here that the UK's Department for International Development comes in, as they are providing £4.5 million ($6.6 million) in new support to finally abolish the last few cases. "What we're announcing today is a new investment and partnership with the Carter Center as we embark on the last push towards zero cases," said the UK's Minister for International Development, Nick Hurd. "The funding will pay for health volunteers, water filters and larvicide in the few remaining endemic villages in South Sudan, Ethiopia, Chad and Mali."

With this last push of extra investment, Carter is confident that the disease can finally be eradicated for good, and soon, although it is often the last few cases of the disease that are the hardest to get rid of. "We were encouraged last year with an 85 percent overall reduction - of 126 cases down to 22 - and so that is a good omen for a fairly quick wrap up," said Carter. "We hope this year we won't have any cases."

And what's next once Guinea worm is finally exiled to the history books? Well the Carter Center is currently working on eight diseases that they think could feasibly be eradicated, with river blindness leading the pack. "We began an experimental project in six countries that had river blindness in Latin America, and we've eliminated it in I'd say 95.5 percent of people," said Carter. If and when they are given the go-ahead by the World Health Organization, the program will be rolled out right across Africa, so that hopefully we can say goodbye to yet another preventable disease.